This invention relates to a connector for interconnecting a plurality of signal tubes such as shock tubes.
In a typical shock tube detonating system use is made of connectors, as appropriate, to interconnect shock tubes to ensure that correct propagation of a blast signal from one shock tube to another is reliably achieved. A single failure in the propagation process can result in a blast not being produced according to design, and this can cause significant production losses or downtime.
Shock tube initiating systems are in widespread use in the mining industry, in underground and in open pit environments. Connectors which are used to interconnect the shock tubes vary according to the number of shock tubes which must be coupled together. A typical connector is made in an injection moulding process and is designed to hold a detonator which, when fired, initiates shock tubes which are fixed to the connector. Normally the shock tubes, at a location at which the shock tubes are coupled to the connector, are held so that they are perpendicularly disposed relative to an elongate axis of the detonator.
Each shock tube should be securely attached to the connector and should not be capable of becoming inadvertently separated from the connector. One problem in this respect is that, as the number of shock tubes which are directly coupled to a single connector increases, the likelihood that the shock tubes can become detached from the connector also increases. It should be borne in mind that the shock tubes can be subjected to substantial tensile forces, particularly when used in rough mining conditions. A limited retentive force is available from a typical connector and this retentive force may not be sufficient to retain a number of shock tubes firmly anchored to a connector while an explosive system is being established. Another factor is that a detonator which is engaged with the connector may be movable slightly in a longitudinal direction relative to the connector. This type of movement can create a small gap between one or more of the shock tubes and the detonator and this, in turn, may adversely affect the firing of the shock tubes when the detonator is ignited.
By way of background information reference is made, for example, to U.S. Pat. No. 5,703,319 which discloses a connector block in which is formed an arcuate line-retaining slot disposed transversely to a longitudinal axis of a detonator at an output end of the detonator. This type of arrangement can be used only with a limited number of shock tubes. A similar observation is made with respect to the connector block disclosed in the specification of U.S. Pat. No. 7,798,065.
U.S. Pat. No. 5,204,492 discloses an arrangement in which shock tubes, coupled to a connector, are disposed generally parallel to each other and to a longitudinal axis of a detonator in a circumferential array around the detonator. A number of different connector designs are described, but there is no disclosure of an arrangement in which a connector can be coupled to a large number of shock tubes, e.g. 10 or more.
An object of the present invention is to provide a signal tube connector which can be used with a significant number of shock tubes and which, at least to some extent, addresses the aforementioned operational requirements.